You may have read my post about the challenges I encountered in hosting Gigapixel and Pano-Tour content with SquareSpace, if you don't have time to follow the link, the short story is don't waist too much time trying. I found several dead ends, and you might be able to find some success, but most likely your better off hosting that content somewhere else. I use Amazon Web Services, they have a free tier that might meet your needs and very affordable options for larger content. Once it is hosted elsewhere you can embed that content in your SquareSpace pages - and they look and work great with your beautiful SquareSpace templates. Here are a couple of pieces of advice on how to use Complex Flash/HTML5 code on your SquareSpace page.